Hydrogen is stored conventionally as a gas or liquid. Hydrogen, due to its very low density, it is stored at very high pressures (more than 3000 psi) or as liquid hydrogen at a very low temperature of −253° C. To increase the storage density of hydrogen the application of metal hydride is adopted as an alternative method. The alkali metals and alkaline earth metals and also some of their hydrides and mixed metal hydrides are also used to generate Hydrogen on reaction with water. Sodium Hydride is an inexpensive metal hydride that is produced in bulk and hence generally preferred for the storage of hydrogen.
The following are the some of the advantages of storing hydrogen in metal hydrides: eliminates high pressure and cryogenic temperature storage, eliminates carbon emission observed in reforming of Methane and Methanol, production of the desired quantity of hydrogen only when required, and recycling of metal hydroxide to produce metal hydride.
The hydrogen from metal hydride is produced either by heating metal hydride to above 400° C. or by reacting the metal hydride with water.
In heating process, the metal hydrides are extruded as rods, and are decomposed by heating them by means of electrical heaters or flue gas. The temperature for the decomposition is usually at about 400° C. The hydrogen is absorbed over the alkaline metal at high pressure and temperature.2NaH→2Na+H2 
The other alternate method of producing hydrogen is by reacting the metal hydride with water.NaH+H2O→NaOH+H2 
In the case of reaction by decomposition the amount of hydrogen produced is about 50% less when compared with the reaction of metal hydride with water.
Metal Hydride Decomposition System in Automobiles
The requirement of pure hydrogen being a fundamental requirement in fuel cells or IC engines, the metal hydride rods have to be indirectly heated either by an electrical heater or by a flue gas. A separate energy source has to be provided for heating the metal hydrides, resulting in the occupation of more space in the automobile. Another limitation in the process is that factors pertaining to the production and absorption of Hydrogen vary during each recycling, since the metal hydride lattice starts cracking.
In a conventional hydrogen production system as depicted in FIG. 1 of the accompanied diagrams, wherein the reactor adopts the following reaction in a reactor:NaH+H2O→NaOH+H2 
In this process, wherein the sodium hydride in the form of a ball having lesser density than water floats up and the unbroken plastic balls (1.3) are cut into two pieces at the topside of the reactor (1.6) by means of ramming devices (1.5) to enable the sodium hydride to react with water to produce hydrogen. The broken (1.2) pieces float in the upper region of the reaction chamber (1.6). However, the limitation of this process is that if the metal hydride thus used is heavier than water, in such an event a separate reactor is required for high density metal hydrides. An alkali storage device (1.4) is disposed to collect alkali as a byproduct. In the above-stated process, the metal hydrides are first formed into a spherical ball of about ping pong ball size and coated with flexible polyethylene jacket made of the following polymeric materials, polyethylene, polypropylene, Kraton, SBR, Noryl, Peek etc. In the above-stated conventional process hydrogen storage device (1.1) is different from the reaction chamber (1.6).
Limitations encountered in the conventional water treatment processes include in an upside down reactor system, dispensing of the metal hydride ball cannot be adopted, if the metal hydride balls are heavier than water, mixed metal hydrides like NaAlH that are adopted in the conventional processes are not readily available. It is also expensive to manufacture NaAlH exclusively for metal hydride project to generate Hydrogen. Flexible polyethylene balls that are used to store metal hydrides, conventionally, do not open out but only get crushed, which may result in the malfunctioning of the dispensing system. Further, a separate hydrogen storage tank, that is adopted in reactor system, along with dispensing unit, results in duplication of safety and control systems in addition to the addition of other components.
Accordingly, in view of the above limitations, in the present invention, spherical ball flow dynamics and disintegration of low density materials have been studied. During the studies, it was observed that the conventional flexible plastic balls can be opened only when they are sliced into two pieces with sharp chisel like object. It is also further observed that when the brittle plastic balls are used for storing the metal hydrides, they disintegrate into small and tiny pieces, on impact with objects having blunt surfaces.